Pick the default gcc/g++ from distro

Author: Bronek

docker/debian/Dockerfile

@@ -143,7 +143,7 @@ RUN conan profile show
 # Test the image by compiling a simple C++ program.
 RUN --mount=type=bind,source=test,target=/test,readonly <<EOF
 cp -r /test test
-cd test && ./run.sh
+cd test && ./run.sh gcc
 cd ..
 rm -rf test
 EOF
@@ -154,19 +154,12 @@ FROM base AS clang
 # This is not inherited from base image, ensure no manual interaction needed.
 ARG DEBIAN_FRONTEND=noninteractive
 
-# Some build dependencies require GCC to be available.
-COPY --from=gcc-src /usr/local/ /usr/local/
-COPY --from=gcc-src /etc/ld.so.conf.d/*.conf /etc/ld.so.conf.d/
+# Some build dependencies require GCC to be also available.
 RUN <<EOF
-ldconfig -v
-dpkg-divert --divert /usr/bin/gcc.orig --rename /usr/bin/gcc
-update-alternatives --install /usr/bin/gcc gcc /usr/local/bin/gcc 100
-update-alternatives --install \
-  /usr/bin/gcc gcc /usr/local/bin/gcc 100 \
-  --slave /usr/bin/g++ g++ /usr/local/bin/g++ \
-  --slave /usr/bin/gcc-ar gcc-ar /usr/local/bin/gcc-ar \
-  --slave /usr/bin/gcc-nm gcc-nm /usr/local/bin/gcc-nm \
-  --slave /usr/bin/gcc-ranlib gcc-ranlib /usr/local/bin/gcc-ranlib
+apt-get update
+apt-get install -y --no-install-recommends gcc g++
+apt-get clean
+rm -rf /var/lib/apt/lists/*
 EOF
 
 # Install Clang. Use the LLVM apt repository to access the latest versions. We
@@ -245,7 +238,7 @@ RUN conan profile show
 # Test the image by compiling a simple C++ program.
 RUN --mount=type=bind,source=test,target=/test,readonly <<EOF
 cp -r /test test
-cd test && ./run.sh
+cd test && ./run.sh clang
 cd ..
 rm -rf test
 EOF

docker/rhel/Dockerfile

@@ -110,7 +110,7 @@ RUN conan profile show
 # Test the image by compiling a simple C++ program.
 RUN --mount=type=bind,source=test,target=/test,readonly <<EOF
 cp -r /test test
-cd test && ./run.sh
+cd test && ./run.sh gcc
 cd ..
 rm -rf test
 EOF
@@ -119,9 +119,10 @@ EOF
 FROM base AS clang
 
 # Install Clang. Note that in the RHEL UBIs, we cannot choose the Clang version
-# to install and we get what is available.
+# to install and we get what is available. Some build dependencies require GCC
+# to be also available.
 RUN <<EOF
-dnf install -y --setopt=tsflags=nodocs clang llvm
+dnf install -y --setopt=tsflags=nodocs clang llvm gcc gcc-c++
 dnf clean -y all
 rm -rf /var/cache/dnf/*
 update-alternatives --install /usr/bin/cc cc /usr/bin/clang 999
@@ -180,7 +181,7 @@ RUN conan profile show
 # Test the image by compiling a simple C++ program.
 RUN --mount=type=bind,source=test,target=/test,readonly <<EOF
 cp -r /test test
-cd test && ./run.sh
+cd test && ./run.sh clang
 cd ..
 rm -rf test
 EOF

docker/ubuntu/Dockerfile

@@ -128,7 +128,7 @@ RUN conan profile show
 # Test the image by compiling a simple C++ program.
 RUN --mount=type=bind,source=test,target=/test,readonly <<EOF
 cp -r /test test
-cd test && ./run.sh
+cd test && ./run.sh gcc
 cd ..
 rm -rf test
 EOF
@@ -139,19 +139,12 @@ FROM base AS clang
 # This is not inherited from base image, ensure no manual interaction needed.
 ARG DEBIAN_FRONTEND=noninteractive
 
-# Some build dependencies require GCC to be available.
-ARG GCC_VERSION
+# Some build dependencies require GCC to be also available.
 RUN <<EOF
 apt-get update
-apt-get install -y --no-install-recommends \
-    gcc-${GCC_VERSION} \
-    g++-${GCC_VERSION} \
-    debhelper
+apt-get install -y --no-install-recommends gcc g++
 apt-get clean
 rm -rf /var/lib/apt/lists/*
-update-alternatives \
-    --install /usr/bin/gcc gcc /usr/bin/gcc-${GCC_VERSION} 100 \
-    --slave /usr/bin/g++ g++ /usr/bin/g++-${GCC_VERSION}
 EOF
 
 # Install Clang.
@@ -225,7 +218,7 @@ RUN conan profile show
 # Test the image by compiling a simple C++ program.
 RUN --mount=type=bind,source=test,target=/test,readonly <<EOF
 cp -r /test test
-cd test && ./run.sh
+cd test && ./run.sh clang
 cd ..
 rm -rf test
 EOF

test/run.sh

@@ -1,6 +1,7 @@
 #!/bin/bash
 
 set -ex
+set -o pipefail
 
 # Install Conan dependencies, configure the project, and build the executable.
 conan install . --output-folder=build --build=missing
@@ -9,7 +10,7 @@ cmake .. -DCMAKE_TOOLCHAIN_FILE=conan_toolchain.cmake -DCMAKE_BUILD_TYPE=Release
 cmake --build .
 
 # Run the executable.
-./example
+./example | grep -E "^Compiler used: $1$"
 
 # Remove the Conan dependencies.
 conan remove -c "*"

test/src/main.cpp

@@ -30,5 +30,14 @@ int main(void) {
 
     std::printf("ZLIB VERSION: %s\n", zlibVersion());
 
+#ifdef __clang__
+    constexpr char which[] = "clang";
+#elif __GNUC__
+    constexpr char which[] = "gcc";
+#else
+    constexpr char which[] = "unknown";
+#endif
+    std::printf("Compiler used: %s\n", which);
+
     return EXIT_SUCCESS;
 }